HELP ON DIABETES

Causes of Hypoglycemia
Hypoglycemia in people with diabetes is a consequence of three things: behavioral issues, impaired counterregulatory systems, and complications of diabetes.

BEHAVIORAL ISSUES

Behavioral issues include overestimating carbohydrate intake, failing to adjust insu­lin for exercise, and stacking of insulin and overaggressive treatment of high glu­cose levels.

Overestimation of Carbohydrate Intake

One of the most common reasons for recurrent hypoglycemia is injecting too much insulin or taking too much oral medication for the amount of carbohydrates ingested. You may overestimate the amount of carbohydrate in the food or eat less than planned, or you may be delayed in eating after taking the insulin or medicine. For example, a number of times, I have had patients inject a dose of insulin in the car before they went to a restaurant. At the restaurant, the food did not come at the expected time, and so their glucose level went low. Another example is when patients are asked to fast for a lab test (such as a lipid profile): they do not realize that they should delay taking their insulin or diabetic medicine until after the test. Drinking alcohol in excess , especially on an empty stomach, can also cause hypoglycemia.

Failure to Adjust for Exercise

Hypoglycemia can occur during or even several hours after exercise, and so glucose levels need to be moni­tored and food and insulin adjusted. Failure to do this can lead to hypoglycemia. Unexpected exercise can also be a challenge:

“Stacking” Insulin and Overaggressive Treatment of High Glucose Levels

  Some people with diabetes do not like their glucose levels to be high, and they treat every high glucose level aggressively. These individuals who “stack” their insulin— that is, give another dose of insulin before the first injection has had its full action— can leave themselves open to hypoglycemia. A common mistake is to give insulin before a meal and then check the glucose level again an hour or two later and give additional insulin without realizing that the premeal insulin is still getting absorbed. To protect against stacking, the new insulin pumps have an “insulin-on-board” fea­ture that keeps track of when the last insulin bolus was given and will remind the user that some of the previous insulin bolus is still getting absorbed if they attempt to give additional insulin.

FAILURE OF COUNTERREGULATORY SYSTEMS

  Counterregulatory systems are those systems of the body—hormones and the ner­vous system—that are activated in response to falling glucose levels. In people with long-standing diabetes, some of the counterregulatory systems may not work as effectively, and this impairs the body’s ability to respond adequately to falling glu­cose levels.

Lack of Glucagon Response

In new onset diabetes, glucagon levels rise in response to a falling glucose level, and this is the most important factor preventing a further fall in the glucose level. People with diabetes longer than five years lose this glucagon response. As a result, these individuals are at a significant disadvantage in protecting themselves against falling glucose levels. People who have diabetes because of pancreatitis or pancreatic sur­gery also lack glucagon and so are at increased risk for hypoglycemia.

Deficiency in Adrenaline and Noradrenaline Responses

  Once the glucagon response is lost, the release of adrenaline and noradrenaline from the adrenal glands takes on added importance, alerting you to the falling glu­cose by causing your heart to race and making you shake. The adrenaline and nor­adrenaline responses are not as strong in people who have hypoglycemic unaware­ness due to repeated low glucose levels.

Cortisol Deficiency

The adrenal gland releases cortisol, a counterregulatory hormone that raises glu­cose. A defi ciency of cortisol can increase the risk of hypoglycemia. Occasionally, people with type 1 diabetes can develop adrenal failure (Addison’s disease). When this happens, their insulin requirements fall significantly, and unless their insulin dose is cut back, they will get hypoglycemic.

DIABETES COMPLICATIONS

Complications of diabetes include autonomic neuropathy, gastroparesis, and kidney failure.

Autonomic Neuropathy

The sympathetic nervous system is an important counterregulatory system that alerts a person that his or her glucose level is falling by causing symptoms such as shaking, a racing heart, and sweating. Failure of this system increases the risk of hypoglycemia.

Gastroparesis

Damage to the nerves to the stomach (gastroparesis) can delay food emptying, and if the insulin has been given before the meal, the peak of insulin action may occur before the food is absorbed, causing hypoglycemia.

Kidney Failure

People with diabetes who have kidney failure are at higher risk of hypoglycemia. There are several reasons for this. First, in kidney failure, the injected insulin and some of the oral diabetes medicines stay in the body for longer than normal. Sec­ond, people with kidney failure may have poor appetite and can get malnourished. The decreased fat and muscle mass due to malnutrition can impair